This section provides background information related to the present disclosure which is not necessarily prior art.
A battery assembly for hybrid, plug-in electric (EV), or other type vehicles includes a plurality of battery cells. Cooling fins, repeating frames and foams, and the battery cells are stacked to form a battery module or battery pack. The battery module for a long driving range EV may contain hundreds of battery cells.
Currently, after stacking and assembling the battery cells and other components into the battery module, every two or three adjacent battery cells are welded together with U-channel bus bar sheet metals to form serial/parallel electric connections. Specifically, each of the battery cells has at least two tabs or electric terminals (one positive, one negative) that are welded to the U-channel bus bar sheet metals. In certain applications, the tabs of each of the battery cells are bent such that the tips of the tabs are aligned after welding. Unfortunately, due to the difficulty of precise tab bending and position control during welding, uneven tab height still exists. Uneven and misaligned tabs affect the overall weld quality between the tabs and the U-channel bus bar sheets. Furthermore, because of the irreversible nature of current welding techniques, such as laser welding and ultrasonic welding, removing a defective or “bad” battery cell from a fully assembled battery module requires cutting all of the tab connections in the battery module, thereby rendering the “good” battery cells unusable for re-weld or restoration to another battery module.
It would be desirable to develop a battery module and a method of assembling the battery module that is more reliable and less susceptible to defects.